Looks like it could be a rover disc on the wall.
Being a side throw mower you would only need flat blades on it.
A bit of a tip, if you need the disc to be smaller diameter, get a set of new blades that suit do all the measurements, bolt them all together clamp them in the vice and cut them all off at once. Instantly ballanced.
The boss is a 3 bolt pattern. Regular rover is smallest. Masport is a bigger spread (and 6mm bolts rather than 1/4" UNF) and i thnk theres an in between. Then the wide cut rovers are bigger, but they are huge by comparison.
You can buy a universal blade disc that will take different type blades, and put baby bob blades on it.
Older rover side throws have a small disc., smaller than the regular 18" disc. Then longer blades.
You can also use the smaller disc on the wide cut rovers with Honda blades.
Ive had this blade disc stuff do my head in over and over. lol.
